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Diffstat (limited to 'src/gfxstream/common/etc/etc.cpp')
| -rw-r--r-- | src/gfxstream/common/etc/etc.cpp | 1031 |
1 files changed, 1031 insertions, 0 deletions
diff --git a/src/gfxstream/common/etc/etc.cpp b/src/gfxstream/common/etc/etc.cpp new file mode 100644 index 00000000000..18b2596ac1d --- /dev/null +++ b/src/gfxstream/common/etc/etc.cpp @@ -0,0 +1,1031 @@ +// Copyright 2009 Google Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "gfxstream/etc.h" + +#include <algorithm> +#include <assert.h> +#include <string.h> +#include <stdint.h> +#include <stdio.h> + +typedef uint16_t etc1_uint16; + +/* From http://www.khronos.org/registry/gles/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt + + The number of bits that represent a 4x4 texel block is 64 bits if + <internalformat> is given by ETC1_RGB8_OES. + + The data for a block is a number of bytes, + + {q0, q1, q2, q3, q4, q5, q6, q7} + + where byte q0 is located at the lowest memory address and q7 at + the highest. The 64 bits specifying the block is then represented + by the following 64 bit integer: + + int64bit = 256*(256*(256*(256*(256*(256*(256*q0+q1)+q2)+q3)+q4)+q5)+q6)+q7; + + ETC1_RGB8_OES: + + a) bit layout in bits 63 through 32 if diffbit = 0 + + 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 + ----------------------------------------------- + | base col1 | base col2 | base col1 | base col2 | + | R1 (4bits)| R2 (4bits)| G1 (4bits)| G2 (4bits)| + ----------------------------------------------- + + 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 + --------------------------------------------------- + | base col1 | base col2 | table | table |diff|flip| + | B1 (4bits)| B2 (4bits)| cw 1 | cw 2 |bit |bit | + --------------------------------------------------- + + + b) bit layout in bits 63 through 32 if diffbit = 1 + + 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 + ----------------------------------------------- + | base col1 | dcol 2 | base col1 | dcol 2 | + | R1' (5 bits) | dR2 | G1' (5 bits) | dG2 | + ----------------------------------------------- + + 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 + --------------------------------------------------- + | base col 1 | dcol 2 | table | table |diff|flip| + | B1' (5 bits) | dB2 | cw 1 | cw 2 |bit |bit | + --------------------------------------------------- + + + c) bit layout in bits 31 through 0 (in both cases) + + 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 + ----------------------------------------------- + | most significant pixel index bits | + | p| o| n| m| l| k| j| i| h| g| f| e| d| c| b| a| + ----------------------------------------------- + + 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 + -------------------------------------------------- + | least significant pixel index bits | + | p| o| n| m| l| k| j| i| h| g| f| e| d| c | b | a | + -------------------------------------------------- + + + Add table 3.17.2: Intensity modifier sets for ETC1 compressed textures: + + table codeword modifier table + ------------------ ---------------------- + 0 -8 -2 2 8 + 1 -17 -5 5 17 + 2 -29 -9 9 29 + 3 -42 -13 13 42 + 4 -60 -18 18 60 + 5 -80 -24 24 80 + 6 -106 -33 33 106 + 7 -183 -47 47 183 + + + Add table 3.17.3 Mapping from pixel index values to modifier values for + ETC1 compressed textures: + + pixel index value + --------------- + msb lsb resulting modifier value + ----- ----- ------------------------- + 1 1 -b (large negative value) + 1 0 -a (small negative value) + 0 0 a (small positive value) + 0 1 b (large positive value) + + ETC2 codec: + from https://www.khronos.org/registry/gles/specs/3.0/es_spec_3.0.4.pdf + page 289 + */ + +static const int kRGBModifierTable[] = { +/* 0 */2, 8, -2, -8, +/* 1 */5, 17, -5, -17, +/* 2 */9, 29, -9, -29, +/* 3 */13, 42, -13, -42, +/* 4 */18, 60, -18, -60, +/* 5 */24, 80, -24, -80, +/* 6 */33, 106, -33, -106, +/* 7 */47, 183, -47, -183 }; + +static const int kRGBOpaqueModifierTable[] = { +/* 0 */0, 8, 0, -8, +/* 1 */0, 17, 0, -17, +/* 2 */0, 29, 0, -29, +/* 3 */0, 42, 0, -42, +/* 4 */0, 60, 0, -60, +/* 5 */0, 80, 0, -80, +/* 6 */0, 106, 0, -106, +/* 7 */0, 183, 0, -183 }; + +static const int kAlphaModifierTable[] = { +/* 0 */ -3, -6, -9, -15, 2, 5, 8, 14, +/* 1 */ -3, -7, -10, -13, 2, 6, 9, 12, +/* 2 */ -2, -5, -8, -13, 1, 4, 7, 12, +/* 3 */ -2, -4, -6, -13, 1, 3, 5, 12, +/* 4 */ -3, -6, -8, -12, 2, 5, 7, 11, +/* 5 */ -3, -7, -9, -11, 2, 6, 8, 10, +/* 6 */ -4, -7, -8, -11, 3, 6, 7, 10, +/* 7 */ -3, -5, -8, -11, 2, 4, 7, 10, +/* 8 */ -2, -6, -8, -10, 1, 5, 7, 9, +/* 9 */ -2, -5, -8, -10, 1, 4, 7, 9, +/* 10 */ -2, -4, -8, -10, 1, 3, 7, 9, +/* 11 */ -2, -5, -7, -10, 1, 4, 6, 9, +/* 12 */ -3, -4, -7, -10, 2, 3, 6, 9, +/* 13 */ -1, -2, -3, -10, 0, 1, 2, 9, +/* 14 */ -4, -6, -8, -9, 3, 5, 7, 8, +/* 15 */ -3, -5, -7, -9, 2, 4, 6, 8 +}; + +static const int kLookup[8] = { 0, 1, 2, 3, -4, -3, -2, -1 }; + +static inline int clamp(int x) { + return (x >= 0 ? (x < 255 ? x : 255) : 0); +} + +static inline int clamp2047(int x) { + return (x >= 0 ? (x < 2047 ? x : 2047) : 0); +} + +static inline int clampSigned1023(int x) { + return (x >= -1023 ? (x < 1023 ? x : 1023) : -1023); +} + +static +inline int convert4To8(int b) { + int c = b & 0xf; + return (c << 4) | c; +} + +static +inline int convert5To8(int b) { + int c = b & 0x1f; + return (c << 3) | (c >> 2); +} + +static +inline int convert6To8(int b) { + int c = b & 0x3f; + return (c << 2) | (c >> 4); +} + +static +inline int convert7To8(int b) { + int c = b & 0x7f; + return (c << 1) | (c >> 6); +} + +static +inline int divideBy255(int d) { + return (d + 128 + (d >> 8)) >> 8; +} + +static +inline int convert8To4(int b) { + int c = b & 0xff; + return divideBy255(c * 15); +} + +static +inline int convert8To5(int b) { + int c = b & 0xff; + return divideBy255(c * 31); +} + +static +inline int convertDiff(int base, int diff) { + return convert5To8((0x1f & base) + kLookup[0x7 & diff]); +} +static +int isOverflowed(int base, int diff) { + int val = (0x1f & base) + kLookup[0x7 & diff]; + return val < 0 || val >= 32; +} + +static +void decode_subblock(etc1_byte* pOut, int r, int g, int b, const int* table, + etc1_uint32 low, bool second, bool flipped, bool isPunchthroughAlpha, + bool opaque) { + int baseX = 0; + int baseY = 0; + int channels = isPunchthroughAlpha ? 4 : 3; + if (second) { + if (flipped) { + baseY = 2; + } else { + baseX = 2; + } + } + for (int i = 0; i < 8; i++) { + int x, y; + if (flipped) { + x = baseX + (i >> 1); + y = baseY + (i & 1); + } else { + x = baseX + (i >> 2); + y = baseY + (i & 3); + } + int k = y + (x * 4); + int msb = ((low >> (k + 15)) & 2); + int lsb = ((low >> k) & 1); + etc1_byte* q = pOut + channels * (x + 4 * y); + if (isPunchthroughAlpha && !opaque && msb && !lsb) { + // rgba all 0 + memset(q, 0, 4); + q += 4; + } else { + int offset = lsb | msb; + int delta = table[offset]; + *q++ = clamp(r + delta); + *q++ = clamp(g + delta); + *q++ = clamp(b + delta); + if (isPunchthroughAlpha) { + *q++ = 255; + } + } + } +} + +static void etc2_T_H_index(const int* clrTable, etc1_uint32 low, + bool isPunchthroughAlpha, bool opaque, + etc1_byte* pOut) { + etc1_byte* q = pOut; + for (int y = 0; y < 4; y++) { + for (int x = 0; x < 4; x++) { + int k = y + x * 4; + int msb = (low >> (k + 15)) & 2; + int lsb = (low >> k) & 1; + if (isPunchthroughAlpha && !opaque && msb && !lsb) { + // rgba all 0 + memset(q, 0, 4); + q += 4; + } else { + int offset = lsb | msb; + for (int c = 0; c < 3; c++) { + *q++ = clrTable[offset*3 + c]; + } + if (isPunchthroughAlpha) { + *q++ = 255; + } + } + } + } +} + +// ETC2 codec: +// from https://www.khronos.org/registry/gles/specs/3.0/es_spec_3.0.4.pdf +// page 289 + +static void etc2_decode_block_T(etc1_uint32 high, etc1_uint32 low, + bool isPunchthroughAlpha, bool opaque, etc1_byte* pOut) { + const int LUT[] = {3, 6, 11, 16, 23, 32, 41, 64}; + int r1, r2, g1, g2, b1, b2; + r1 = convert4To8((((high >> 27) & 3) << 2) | ((high >> 24) & 3)); + g1 = convert4To8(high >> 20); + b1 = convert4To8(high >> 16); + r2 = convert4To8(high >> 12); + g2 = convert4To8(high >> 8); + b2 = convert4To8(high >> 4); + // 3 bits intense modifier + int intenseIdx = (((high >> 2) & 3) << 1) | (high & 1); + int intenseMod = LUT[intenseIdx]; + int clrTable[12]; + clrTable[0] = r1; + clrTable[1] = g1; + clrTable[2] = b1; + clrTable[3] = clamp(r2 + intenseMod); + clrTable[4] = clamp(g2 + intenseMod); + clrTable[5] = clamp(b2 + intenseMod); + clrTable[6] = r2; + clrTable[7] = g2; + clrTable[8] = b2; + clrTable[9] = clamp(r2 - intenseMod); + clrTable[10] = clamp(g2 - intenseMod); + clrTable[11] = clamp(b2 - intenseMod); + etc2_T_H_index(clrTable, low, isPunchthroughAlpha, opaque, pOut); +} + +static void etc2_decode_block_H(etc1_uint32 high, etc1_uint32 low, + bool isPunchthroughAlpha, bool opaque, etc1_byte* pOut) { + const int LUT[] = {3, 6, 11, 16, 23, 32, 41, 64}; + int r1, r2, g1, g2, b1, b2; + r1 = convert4To8(high >> 27); + g1 = convert4To8((high >> 24) << 1 | ((high >> 20) & 1)); + b1 = convert4To8((high >> 19) << 3 | ((high >> 15) & 7)); + r2 = convert4To8(high >> 11); + g2 = convert4To8(high >> 7); + b2 = convert4To8(high >> 3); + // 3 bits intense modifier + int intenseIdx = high & 4; + intenseIdx |= (high & 1) << 1; + intenseIdx |= (((r1 << 16) | (g1 << 8) | b1) >= ((r2 << 16) | (g2 << 8) | b2)); + int intenseMod = LUT[intenseIdx]; + int clrTable[12]; + clrTable[0] = clamp(r1 + intenseMod); + clrTable[1] = clamp(g1 + intenseMod); + clrTable[2] = clamp(b1 + intenseMod); + clrTable[3] = clamp(r1 - intenseMod); + clrTable[4] = clamp(g1 - intenseMod); + clrTable[5] = clamp(b1 - intenseMod); + clrTable[6] = clamp(r2 + intenseMod); + clrTable[7] = clamp(g2 + intenseMod); + clrTable[8] = clamp(b2 + intenseMod); + clrTable[9] = clamp(r2 - intenseMod); + clrTable[10] = clamp(g2 - intenseMod); + clrTable[11] = clamp(b2 - intenseMod); + etc2_T_H_index(clrTable, low, isPunchthroughAlpha, opaque, pOut); +} + +static void etc2_decode_block_P(etc1_uint32 high, etc1_uint32 low, + bool isPunchthroughAlpha, etc1_byte* pOut) { + int ro, go, bo, rh, gh, bh, rv, gv, bv; + uint64_t data = high; + data = data << 32 | low; + ro = convert6To8(data >> 57); + go = convert7To8((data >> 56 << 6) | ((data >> 49) & 63)); + bo = convert6To8((data >> 48 << 5) + | (((data >> 43) & 3 ) << 3) + | ((data >> 39) & 7)); + rh = convert6To8((data >> 34 << 1) | ((data >> 32) & 1)); + gh = convert7To8(data >> 25); + bh = convert6To8(data >> 19); + rv = convert6To8(data >> 13); + gv = convert7To8(data >> 6); + bv = convert6To8(data); + etc1_byte* q = pOut; + for (int i = 0; i < 16; i++) { + int y = i >> 2; + int x = i & 3; + *q++ = clamp((x * (rh - ro) + y * (rv - ro) + 4 * ro + 2) >> 2); + *q++ = clamp((x * (gh - go) + y * (gv - go) + 4 * go + 2) >> 2); + *q++ = clamp((x * (bh - bo) + y * (bv - bo) + 4 * bo + 2) >> 2); + if (isPunchthroughAlpha) *q++ = 255; + } +} + +// Input is an ETC1 / ETC2 compressed version of the data. +// Output is a 4 x 4 square of 3-byte pixels in form R, G, B +// ETC2 codec: +// from https://www.khronos.org/registry/gles/specs/3.0/es_spec_3.0.4.pdf +// page 289 + +void etc2_decode_rgb_block(const etc1_byte* pIn, bool isPunchthroughAlpha, + etc1_byte* pOut) { + etc1_uint32 high = (pIn[0] << 24) | (pIn[1] << 16) | (pIn[2] << 8) | pIn[3]; + etc1_uint32 low = (pIn[4] << 24) | (pIn[5] << 16) | (pIn[6] << 8) | pIn[7]; + bool opaque = (high >> 1) & 1; + int r1, r2, g1, g2, b1, b2; + if (isPunchthroughAlpha || high & 2) { + // differential + int rBase = high >> 27; + int gBase = high >> 19; + int bBase = high >> 11; + if (isOverflowed(rBase, high >> 24)) { + etc2_decode_block_T(high, low, isPunchthroughAlpha, opaque, pOut); + return; + } + if (isOverflowed(gBase, high >> 16)) { + etc2_decode_block_H(high, low, isPunchthroughAlpha, opaque, pOut); + return; + } + if (isOverflowed(bBase, high >> 8)) { + etc2_decode_block_P(high, low, isPunchthroughAlpha, pOut); + return; + } + r1 = convert5To8(rBase); + r2 = convertDiff(rBase, high >> 24); + g1 = convert5To8(gBase); + g2 = convertDiff(gBase, high >> 16); + b1 = convert5To8(bBase); + b2 = convertDiff(bBase, high >> 8); + } else { + // not differential + r1 = convert4To8(high >> 28); + r2 = convert4To8(high >> 24); + g1 = convert4To8(high >> 20); + g2 = convert4To8(high >> 16); + b1 = convert4To8(high >> 12); + b2 = convert4To8(high >> 8); + } + int tableIndexA = 7 & (high >> 5); + int tableIndexB = 7 & (high >> 2); + const int* rgbModifierTable = opaque || !isPunchthroughAlpha ? + kRGBModifierTable : kRGBOpaqueModifierTable; + const int* tableA = rgbModifierTable + tableIndexA * 4; + const int* tableB = rgbModifierTable + tableIndexB * 4; + bool flipped = (high & 1) != 0; + decode_subblock(pOut, r1, g1, b1, tableA, low, false, flipped, + isPunchthroughAlpha, opaque); + decode_subblock(pOut, r2, g2, b2, tableB, low, true, flipped, + isPunchthroughAlpha, opaque); +} + +void eac_decode_single_channel_block(const etc1_byte* pIn, + int decodedElementBytes, bool isSigned, + etc1_byte* pOut) { + assert(decodedElementBytes == 1 || decodedElementBytes == 2 || decodedElementBytes == 4); + int base_codeword = isSigned ? reinterpret_cast<const char*>(pIn)[0] + : pIn[0]; + if (base_codeword == -128) base_codeword = -127; + int multiplier = pIn[1] >> 4; + int tblIdx = pIn[1] & 15; + const int* table = kAlphaModifierTable + tblIdx * 8; + const etc1_byte* p = pIn + 2; + // position in a byte of the next 3-bit index: + // | a a a | b b b | c c c | d d d ... + // | byte | byte... + int bitOffset = 5; + for (int i = 0; i < 16; i ++) { + // flip x, y in output + int outIdx = (i % 4) * 4 + i / 4; + etc1_byte* q = pOut + outIdx * decodedElementBytes; + + int modifier = 0; + if (bitOffset < 0) { // (Part of) the index is in the next byte. + modifier += p[0] << (-bitOffset); + p ++; + bitOffset += 8; + } + modifier += p[0] >> bitOffset; + modifier &= 7; + bitOffset -= 3; // move to the next index + if (bitOffset == -3) { + bitOffset = 5; + p++; + } + int modifierValue = table[modifier]; + int decoded = base_codeword + modifierValue * multiplier; + if (decodedElementBytes == 1) { + *q = clamp(decoded); + } else { // decodedElementBytes == 4 + decoded *= 8; + if (multiplier == 0) { + decoded += modifierValue; + } + if (isSigned) { + decoded = clampSigned1023(decoded); + reinterpret_cast<float*>(q)[0] = (float)decoded / 1023.0; + } else { + decoded += 4; + decoded = clamp2047(decoded); + reinterpret_cast<float*>(q)[0] = (float)decoded / 2047.0; + } + } + } +} + +typedef struct { + etc1_uint32 high; + etc1_uint32 low; + etc1_uint32 score; // Lower is more accurate +} etc_compressed; + +static +inline void take_best(etc_compressed* a, const etc_compressed* b) { + if (a->score > b->score) { + *a = *b; + } +} + +static +void etc_average_colors_subblock(const etc1_byte* pIn, etc1_uint32 inMask, + etc1_byte* pColors, bool flipped, bool second) { + int r = 0; + int g = 0; + int b = 0; + + if (flipped) { + int by = 0; + if (second) { + by = 2; + } + for (int y = 0; y < 2; y++) { + int yy = by + y; + for (int x = 0; x < 4; x++) { + int i = x + 4 * yy; + if (inMask & (1 << i)) { + const etc1_byte* p = pIn + i * 3; + r += *(p++); + g += *(p++); + b += *(p++); + } + } + } + } else { + int bx = 0; + if (second) { + bx = 2; + } + for (int y = 0; y < 4; y++) { + for (int x = 0; x < 2; x++) { + int xx = bx + x; + int i = xx + 4 * y; + if (inMask & (1 << i)) { + const etc1_byte* p = pIn + i * 3; + r += *(p++); + g += *(p++); + b += *(p++); + } + } + } + } + pColors[0] = (etc1_byte)((r + 4) >> 3); + pColors[1] = (etc1_byte)((g + 4) >> 3); + pColors[2] = (etc1_byte)((b + 4) >> 3); +} + +static +inline int square(int x) { + return x * x; +} + +static etc1_uint32 chooseModifier(const etc1_byte* pBaseColors, + const etc1_byte* pIn, etc1_uint32 *pLow, int bitIndex, + const int* pModifierTable) { + etc1_uint32 bestScore = ~0; + int bestIndex = 0; + int pixelR = pIn[0]; + int pixelG = pIn[1]; + int pixelB = pIn[2]; + int r = pBaseColors[0]; + int g = pBaseColors[1]; + int b = pBaseColors[2]; + for (int i = 0; i < 4; i++) { + int modifier = pModifierTable[i]; + int decodedG = clamp(g + modifier); + etc1_uint32 score = (etc1_uint32) (6 * square(decodedG - pixelG)); + if (score >= bestScore) { + continue; + } + int decodedR = clamp(r + modifier); + score += (etc1_uint32) (3 * square(decodedR - pixelR)); + if (score >= bestScore) { + continue; + } + int decodedB = clamp(b + modifier); + score += (etc1_uint32) square(decodedB - pixelB); + if (score < bestScore) { + bestScore = score; + bestIndex = i; + } + } + etc1_uint32 lowMask = (((bestIndex >> 1) << 16) | (bestIndex & 1)) + << bitIndex; + *pLow |= lowMask; + return bestScore; +} + +static +void etc_encode_subblock_helper(const etc1_byte* pIn, etc1_uint32 inMask, + etc_compressed* pCompressed, bool flipped, bool second, + const etc1_byte* pBaseColors, const int* pModifierTable) { + int score = pCompressed->score; + if (flipped) { + int by = 0; + if (second) { + by = 2; + } + for (int y = 0; y < 2; y++) { + int yy = by + y; + for (int x = 0; x < 4; x++) { + int i = x + 4 * yy; + if (inMask & (1 << i)) { + score += chooseModifier(pBaseColors, pIn + i * 3, + &pCompressed->low, yy + x * 4, pModifierTable); + } + } + } + } else { + int bx = 0; + if (second) { + bx = 2; + } + for (int y = 0; y < 4; y++) { + for (int x = 0; x < 2; x++) { + int xx = bx + x; + int i = xx + 4 * y; + if (inMask & (1 << i)) { + score += chooseModifier(pBaseColors, pIn + i * 3, + &pCompressed->low, y + xx * 4, pModifierTable); + } + } + } + } + pCompressed->score = score; +} + +static bool inRange4bitSigned(int color) { + return color >= -4 && color <= 3; +} + +static void etc_encodeBaseColors(etc1_byte* pBaseColors, + const etc1_byte* pColors, etc_compressed* pCompressed) { + int r1, g1, b1, r2, g2, b2; // 8 bit base colors for sub-blocks + bool differential; + { + int r51 = convert8To5(pColors[0]); + int g51 = convert8To5(pColors[1]); + int b51 = convert8To5(pColors[2]); + int r52 = convert8To5(pColors[3]); + int g52 = convert8To5(pColors[4]); + int b52 = convert8To5(pColors[5]); + + r1 = convert5To8(r51); + g1 = convert5To8(g51); + b1 = convert5To8(b51); + + int dr = r52 - r51; + int dg = g52 - g51; + int db = b52 - b51; + + differential = inRange4bitSigned(dr) && inRange4bitSigned(dg) + && inRange4bitSigned(db); + if (differential) { + r2 = convert5To8(r51 + dr); + g2 = convert5To8(g51 + dg); + b2 = convert5To8(b51 + db); + pCompressed->high |= (r51 << 27) | ((7 & dr) << 24) | (g51 << 19) + | ((7 & dg) << 16) | (b51 << 11) | ((7 & db) << 8) | 2; + } + } + + if (!differential) { + int r41 = convert8To4(pColors[0]); + int g41 = convert8To4(pColors[1]); + int b41 = convert8To4(pColors[2]); + int r42 = convert8To4(pColors[3]); + int g42 = convert8To4(pColors[4]); + int b42 = convert8To4(pColors[5]); + r1 = convert4To8(r41); + g1 = convert4To8(g41); + b1 = convert4To8(b41); + r2 = convert4To8(r42); + g2 = convert4To8(g42); + b2 = convert4To8(b42); + pCompressed->high |= (r41 << 28) | (r42 << 24) | (g41 << 20) | (g42 + << 16) | (b41 << 12) | (b42 << 8); + } + pBaseColors[0] = r1; + pBaseColors[1] = g1; + pBaseColors[2] = b1; + pBaseColors[3] = r2; + pBaseColors[4] = g2; + pBaseColors[5] = b2; +} + +static +void etc_encode_block_helper(const etc1_byte* pIn, etc1_uint32 inMask, + const etc1_byte* pColors, etc_compressed* pCompressed, bool flipped) { + pCompressed->score = ~0; + pCompressed->high = (flipped ? 1 : 0); + pCompressed->low = 0; + + etc1_byte pBaseColors[6]; + + etc_encodeBaseColors(pBaseColors, pColors, pCompressed); + + int originalHigh = pCompressed->high; + + const int* pModifierTable = kRGBModifierTable; + for (int i = 0; i < 8; i++, pModifierTable += 4) { + etc_compressed temp; + temp.score = 0; + temp.high = originalHigh | (i << 5); + temp.low = 0; + etc_encode_subblock_helper(pIn, inMask, &temp, flipped, false, + pBaseColors, pModifierTable); + take_best(pCompressed, &temp); + } + pModifierTable = kRGBModifierTable; + etc_compressed firstHalf = *pCompressed; + for (int i = 0; i < 8; i++, pModifierTable += 4) { + etc_compressed temp; + temp.score = firstHalf.score; + temp.high = firstHalf.high | (i << 2); + temp.low = firstHalf.low; + etc_encode_subblock_helper(pIn, inMask, &temp, flipped, true, + pBaseColors + 3, pModifierTable); + if (i == 0) { + *pCompressed = temp; + } else { + take_best(pCompressed, &temp); + } + } +} + +static void writeBigEndian(etc1_byte* pOut, etc1_uint32 d) { + pOut[0] = (etc1_byte)(d >> 24); + pOut[1] = (etc1_byte)(d >> 16); + pOut[2] = (etc1_byte)(d >> 8); + pOut[3] = (etc1_byte) d; +} + +// Input is a 4 x 4 square of 3-byte pixels in form R, G, B +// inmask is a 16-bit mask where bit (1 << (x + y * 4)) tells whether the corresponding (x,y) +// pixel is valid or not. Invalid pixel color values are ignored when compressing. +// Output is an ETC1 compressed version of the data. + +void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 inMask, + etc1_byte* pOut) { + etc1_byte colors[6]; + etc1_byte flippedColors[6]; + etc_average_colors_subblock(pIn, inMask, colors, false, false); + etc_average_colors_subblock(pIn, inMask, colors + 3, false, true); + etc_average_colors_subblock(pIn, inMask, flippedColors, true, false); + etc_average_colors_subblock(pIn, inMask, flippedColors + 3, true, true); + + etc_compressed a, b; + etc_encode_block_helper(pIn, inMask, colors, &a, false); + etc_encode_block_helper(pIn, inMask, flippedColors, &b, true); + take_best(&a, &b); + writeBigEndian(pOut, a.high); + writeBigEndian(pOut + 4, a.low); +} + +// Return the size of the encoded image data (does not include size of PKM header). + +etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height) { + return (((width + 3) & ~3) * ((height + 3) & ~3)) >> 1; +} + +etc1_uint32 etc_get_encoded_data_size(ETC2ImageFormat format, etc1_uint32 width, + etc1_uint32 height) { + etc1_uint32 size = ((width + 3) & ~3) * ((height + 3) & ~3); + switch (format) { + case EtcRGB8: + case EtcRGB8A1: + case EtcR11: + case EtcSignedR11: + return size >> 1; + case EtcRG11: + case EtcSignedRG11: + case EtcRGBA8: + return size; + default: + assert(0); + return 0; + } +} + +etc1_uint32 etc_get_decoded_pixel_size(ETC2ImageFormat format) { + switch (format) { + case EtcRGB8: + return 3; + case EtcRGBA8: + return 4; + case EtcRGB8A1: + case EtcR11: + case EtcSignedR11: + return 4; + case EtcRG11: + case EtcSignedRG11: + return 8; + default: + assert(0); + return 0; + } +} + +// Encode an entire image. +// pIn - pointer to the image data. Formatted such that the Red component of +// pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset; +// pOut - pointer to encoded data. Must be large enough to store entire encoded image. + +int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height, + etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut) { + if (pixelSize < 2 || pixelSize > 3) { + return -1; + } + static const unsigned short kYMask[] = { 0x0, 0xf, 0xff, 0xfff, 0xffff }; + static const unsigned short kXMask[] = { 0x0, 0x1111, 0x3333, 0x7777, + 0xffff }; + etc1_byte block[ETC1_DECODED_BLOCK_SIZE]; + etc1_byte encoded[ETC1_ENCODED_BLOCK_SIZE]; + + etc1_uint32 encodedWidth = (width + 3) & ~3; + etc1_uint32 encodedHeight = (height + 3) & ~3; + + for (etc1_uint32 y = 0; y < encodedHeight; y += 4) { + etc1_uint32 yEnd = height - y; + if (yEnd > 4) { + yEnd = 4; + } + int ymask = kYMask[yEnd]; + for (etc1_uint32 x = 0; x < encodedWidth; x += 4) { + etc1_uint32 xEnd = width - x; + if (xEnd > 4) { + xEnd = 4; + } + int mask = ymask & kXMask[xEnd]; + for (etc1_uint32 cy = 0; cy < yEnd; cy++) { + etc1_byte* q = block + (cy * 4) * 3; + const etc1_byte* p = pIn + pixelSize * x + stride * (y + cy); + if (pixelSize == 3) { + memcpy(q, p, xEnd * 3); + } else { + for (etc1_uint32 cx = 0; cx < xEnd; cx++) { + int pixel = (p[1] << 8) | p[0]; + *q++ = convert5To8(pixel >> 11); + *q++ = convert6To8(pixel >> 5); + *q++ = convert5To8(pixel); + p += pixelSize; + } + } + } + etc1_encode_block(block, mask, encoded); + memcpy(pOut, encoded, sizeof(encoded)); + pOut += sizeof(encoded); + } + } + return 0; +} + +// Decode an entire image. +// pIn - pointer to encoded data. +// pOut - pointer to the image data. Will be written such that the Red component of +// pixel (x,y) is at pIn + pixelSize * x + stride * y + redOffset. Must be +// large enough to store entire image. + + +int etc2_decode_image(const etc1_byte* pIn, ETC2ImageFormat format, + etc1_byte* pOut, + etc1_uint32 width, etc1_uint32 height, + etc1_uint32 stride) { + etc1_byte block[std::max({ETC1_DECODED_BLOCK_SIZE, + ETC2_DECODED_RGB8A1_BLOCK_SIZE, + EAC_DECODED_R11_BLOCK_SIZE, + EAC_DECODED_RG11_BLOCK_SIZE})]; + etc1_byte alphaBlock[EAC_DECODED_ALPHA_BLOCK_SIZE]; + + etc1_uint32 encodedWidth = (width + 3) & ~3; + etc1_uint32 encodedHeight = (height + 3) & ~3; + + int pixelSize = etc_get_decoded_pixel_size(format); + bool isSigned = (format == EtcSignedR11 || format == EtcSignedRG11); + + for (etc1_uint32 y = 0; y < encodedHeight; y += 4) { + etc1_uint32 yEnd = height - y; + if (yEnd > 4) { + yEnd = 4; + } + for (etc1_uint32 x = 0; x < encodedWidth; x += 4) { + etc1_uint32 xEnd = width - x; + if (xEnd > 4) { + xEnd = 4; + } + switch (format) { + case EtcRGBA8: + eac_decode_single_channel_block(pIn, 1, false, alphaBlock); + pIn += EAC_ENCODE_ALPHA_BLOCK_SIZE; + // Do not break + // Fall through to EtcRGB8 to decode the RGB part + [[fallthrough]]; + case EtcRGB8: + etc2_decode_rgb_block(pIn, false, block); + pIn += ETC1_ENCODED_BLOCK_SIZE; + break; + case EtcRGB8A1: + etc2_decode_rgb_block(pIn, true, block); + pIn += ETC1_ENCODED_BLOCK_SIZE; + break; + case EtcR11: + case EtcSignedR11: + eac_decode_single_channel_block(pIn, 4, isSigned, block); + pIn += EAC_ENCODE_R11_BLOCK_SIZE; + break; + case EtcRG11: + case EtcSignedRG11: + // r channel + eac_decode_single_channel_block(pIn, 4, isSigned, block); + pIn += EAC_ENCODE_R11_BLOCK_SIZE; + // g channel + eac_decode_single_channel_block(pIn, 4, isSigned, + block + EAC_DECODED_R11_BLOCK_SIZE); + pIn += EAC_ENCODE_R11_BLOCK_SIZE; + break; + default: + assert(0); + } + for (etc1_uint32 cy = 0; cy < yEnd; cy++) { + etc1_byte* p = pOut + pixelSize * x + stride * (y + cy); + switch (format) { + case EtcRGB8: + case EtcRGB8A1: + case EtcR11: + case EtcSignedR11: { + const etc1_byte* q = block + (cy * 4) * pixelSize; + memcpy(p, q, xEnd * pixelSize); + } + break; + case EtcRG11: + case EtcSignedRG11: { + const etc1_byte* r = block + cy * EAC_DECODED_R11_BLOCK_SIZE / 4; + const etc1_byte* g = block + cy * EAC_DECODED_R11_BLOCK_SIZE / 4 + EAC_DECODED_R11_BLOCK_SIZE; + int channelSize = pixelSize / 2; + for (etc1_uint32 cx = 0; cx < xEnd; cx++) { + memcpy(p, r, channelSize); + p += channelSize; + r += channelSize; + memcpy(p, g, channelSize); + p += channelSize; + g += channelSize; + } + } + break; + case EtcRGBA8: { + const etc1_byte* q = block + (cy * 4) * 3; + const etc1_byte* qa = alphaBlock + cy * 4; + for (etc1_uint32 cx = 0; cx < xEnd; cx++) { + // copy rgb data + memcpy(p, q, 3); + p += 3; + q += 3; + *p++ = *qa++; + } + } + break; + default: + assert(0); + } + } + } + } + return 0; +} + +static const char kMagic[] = { 'P', 'K', 'M', ' ', '1', '0' }; + +static const etc1_uint32 ETC1_PKM_FORMAT_OFFSET = 6; +static const etc1_uint32 ETC1_PKM_ENCODED_WIDTH_OFFSET = 8; +static const etc1_uint32 ETC1_PKM_ENCODED_HEIGHT_OFFSET = 10; +static const etc1_uint32 ETC1_PKM_WIDTH_OFFSET = 12; +static const etc1_uint32 ETC1_PKM_HEIGHT_OFFSET = 14; + +static const etc1_uint32 ETC1_RGB_NO_MIPMAPS = 0; + +static void writeBEUint16(etc1_byte* pOut, etc1_uint32 data) { + pOut[0] = (etc1_byte) (data >> 8); + pOut[1] = (etc1_byte) data; +} + +static etc1_uint32 readBEUint16(const etc1_byte* pIn) { + return (pIn[0] << 8) | pIn[1]; +} + +// Format a PKM header + +void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height) { + memcpy(pHeader, kMagic, sizeof(kMagic)); + etc1_uint32 encodedWidth = (width + 3) & ~3; + etc1_uint32 encodedHeight = (height + 3) & ~3; + writeBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET, ETC1_RGB_NO_MIPMAPS); + writeBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET, encodedWidth); + writeBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET, encodedHeight); + writeBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET, width); + writeBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET, height); +} + +// Check if a PKM header is correctly formatted. + +etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader) { + if (memcmp(pHeader, kMagic, sizeof(kMagic))) { + return false; + } + etc1_uint32 format = readBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET); + etc1_uint32 encodedWidth = readBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET); + etc1_uint32 encodedHeight = readBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET); + etc1_uint32 width = readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET); + etc1_uint32 height = readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET); + return format == ETC1_RGB_NO_MIPMAPS && + encodedWidth >= width && encodedWidth - width < 4 && + encodedHeight >= height && encodedHeight - height < 4; +} + +// Read the image width from a PKM header + +etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader) { + return readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET); +} + +// Read the image height from a PKM header + +etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader){ + return readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET); +} |